Mildewcide for paint

ABSTRACT

PAINTS CAN BE MADE RESISTANT TO FUNGAL ATTACK BY THE INCORPORATION THEREIN OF 2-(4-THIAZOYL) BENZIMIDAZOLE IN ADMIXTURE WITH A SECOND FUNGICIDE OR MIXTURE OF FUNGICIDES SELECTED FROM ETHYLENEBIS (DITHIOCARBAMIC ACID), ZINC SALT; DIMETHYLDITHIOCARBAMIC ACID, ZINC SALT; 2,4&#39;&#39;,5-TRIBROMOSALICYLANILIDE; TRIBUTYLTIN FLUORIDE OR OXIDE; OR 2-MERCAPTOPYRIDINE-N-OXIDE, ZINC SALT.

Loren I). Brake, Wilmington, Del., assignor to E. I. du Pont de Nemoursand Company, Wilmington, Del. No Drawing. Filed Apr. 18, 1973, Ser. No.352,292 Int. Cl. C09d /14 US. Cl. 106-15 AF 7 Claims ABSTRACT OF THEDISCLOSURE Paints can be made resistant to fungal attack by theincorporation therein of 2-(4-thiazoyl)benzimidazole in admixture with asecond fungicide or mixture of fungicides selected fromethylenebis(dithiocarbamic acid), zinc salt; dimethyldithiocarbamicacid, zinc salt; 3,4',5-tribromosalicylanilide; tributyltin fluoride oroxide; or Z-mercaptopyridine-N-oxide, zinc salt.

BACKGROUND OF THE INVENTION Mercury compounds, such as phenyl mercuricacetate, phenyl mercuric propionate, phenyl mercuric succinate andphenyl mercuric oleate have been used extensively as fungicides infilm-forming compositions such as paint. However, recently the use ofthese mercury compounds is being curtailed in view of possible toxicityproblems, particularly when they are employed at high use levels.

Other types of compounds have been proposed for use as fungicides inpaint, including benzimidazole type fungicides, see US. Pats. 2,933,502,2,933,504, 3,541,213, 3,631,176 and German Patent Application No.2,040,069 published Feb. 17, 1972.

However, the need still exists for a safe fungicide for use in paintcompositions. Difiiculties have been encountered in meeting this needbecause of the special requirements of this use. Thus the fungicide mustnot only provide effective fungicidal protection for an extended periodof time, both in the formulation and in the applied film, but it mustalso be compatible with the other components of the formulation, and itmust not adversely affect the film appearance or properties.

SUMMARY OF THE INVENTION 1 have discovered that a specific mixture offungicides is extremely effective in protecting paint and paint filmfrom fungal attack. The mixture is composed of the followingbenzimidazole compound:

2- (4-thiazoyl) benzimidazole in admixture with a second fungicide ormixture of fungicides selected from (i) ethylenebis(dithiocarbamicacid), zinc salt 51 ornNnils Zn H2 NH-fi -S (ii) dimethyldithiocarbamicacid, zinc salt S 113) zN-ll-S-Jz an raw-1 mi 3,817,762 ented June 18,1974 (iii) 3,4',5-tribromo salicylanilide MGM (iv) tributyltin fluoride(C H SnF (v) tributyltin oxide [(C H Sn] O (vi)2-mercaptopyridine-N-oxide, zinc salt S Zn The above mixture is added topaint in the following proportions from 520,000 parts per million byweight of the benzimidazole and from 550,000 parts per million by weightof the second fungicide or mixture of fungicides.

DESCRIPTION OF THE INVENTION The mixtures of the invention offer a safe,eifective fungicide for film-forming compositions. Fungus mycelia arekilled or prevented from developing by the presence of these mixtures,i.e., the mixture is fungicidal or fungistatic. The mixtures are activeagainst many species of fungi, including the various species of theclasses Pencillium, Aspergillus, Ceratostomella, Aureobasidium,Botrytis, Cladosporium, Fusarium, and Curvularia, which fungi grow onpaint, fabric, paper, wool, fiberboard, and leather goods.

The mixtures of this invention also make possible the control of damageby fungi with an amazingly small amount of chemical and surprisinglylittle effort. These advantages are due in large measure to the factthat the mixtures when properly applied, can prevent the growth of fungiin film-forming compositions. This means that the treated surface can beprotected from fungi with the application of the mixture in thefilm-forming or coating composition. The mixtures also have the propertyof protecting the film-forming composition prior to application, i.e.,they act as fungicidal preservatives for the paint, etc. in thecontainer.

Luggage, shoes, leather, shower curtains, carpets, mats, clothing,grouting, wood, fiberboard, caulks, sealants, adhesives, joint cements,roofing materials, tenting, fabric and other useful household, public orindustrial items are also protected from rot, fungus stains andunsightly mold growth by the mildewcide mixtures of this invention.Either surface or deep protection can be obtained. Surface treatment isby dips, washes, sprays, aerosols or dust applications. Deep treatmentis accomplished by penetrating fungicidal components of the mixture willbe realized if their particle size is less than 50 microns. Largerparticle sizes can, of course, be used; however an effectivedistribution in the resulting film will require higher concentrations toachieve the desired protection. The desired particle size can beobtained using grinders, e.g., sand grinder, ball mills,micropulverizers, air mills, or other methods known in the art. Acombination of two or more of the pulverizing methods may be employed.

The mixture can be incorporated into the film-forming composition in theamounts and by the techniques described in the following paragraphs.

The mixture is present in the compositions in an amount such that solidfilms prepared from the compositions have useful fungicidal propertiesfor the particular end-use application. One skilled in the art, afterrealizing the essence of the invention set forth in this disclosure,will be able to select the fungicide concentration that gives the bestcombination of film physical properties and fungicidal properties in thefinal product for the particular composition and application methodemployed in the practice of this invention. If not enough activefungicide is present, films of the composition will not have suflicientfungicidal properties, either initially or after a short period of use.Iftoo much fungicide is present, films of the composition tend to beunduly expensive.

Coated surfaces and their substrates can be protected from unsightlystain and mold growth by incorporating in the film-forming formulation,prior to application, 5 to 20,000 parts per million by weight of thebenzimidazole and 5 to 50,000 parts per million by weight of the otherfungicide or mixtures thereof. Such treatments with the active mixturealso protect the paint while still in the can from deformation by fungi.

It is preferred that the benzimidazole be in the range of 100-5,000parts per million by weight, the most preferred range is 300-2,000 partsper million by weight.

The other fungicides can be divided into two groups. Group A includesethylenebis (dithiocarbamic acid), zinc salt; dimethyldithiocarbamicacid, zinc salt; and 3,4,5-tribromosalicylanilide. Group B includestributyltin fluoride; tributyltin oxide; and2-rnercaptopyridine-N-oxide, zinc salt.

It is preferred that the compounds of Group A be used in the range ofLOGO-15,000 parts per million by weight, the most preferred range isLOGO-10,000 parts per million by weight. It is preferred that thecompounds of Group B be used in the range of 104,000 parts per millionby weight, the most preferred range is 751,000 parts per million byweight.

The preferred second fungicide selected from Group A is ethylenebis(dithiocarbamic acid), zinc salt and dimethyldithiocarbamic acid, zincsalt; the most preferred is ethylenebis(dithiocarbamic acid), zinc salt;and from Group B is tributyltin fluoride and tributyltin oxide; the mostpreferred is tributyltin fluoride.

The mixtures of the invention often demonstrate improved assistance totunsal attack if the film forming composition contains zinc oxide, e.g.as a pigment.

Preferred embodiments of the novel compositions are in the form ofliquid coating compositions wherein the mixture of film-former and theactive mixture is dispersed in a liquid adapted for use in preparing afilm-former solution or suspension.

For example, very beneficial results are obtainable when the compositionis in the form of a latex paint or latex adhesive wherein (1) the liquidphase is predominantly water (2) the resin or other film-former isinsoluble in the liquid phase, and (3) the film-forming components andthe fungicide mixture are present as very small particles suspended oremulsified in the liquid. I

Good results are also obtainable when the liquid phase in which thefilm-forming components and the fungicide mixture are dispersed ispredominantly a volatile organic liquid, and film-former is present as asolution in said liquid.

The term film-forming compositions as used in this application, is meantto cover paints such as alkyd, acrylic, vinyl acrylic, alkyd modifiedacrylic or alkyd modified vinyl acrylic paints, enamels, lacquers,varnishes, or any other film-former or binder which is known in the artto be useful in the manufacture or solid (nonliquid) films or coatings.The term "film-former refers to the polymer, e.g., synthetic resins,natural resins or elastomers, wax, drying oil component, or mixturesthereof present either in the formulation prior to application or in thefinal film. Film-formers are sometimes referred to the the art asbindeis, especially in compositions containing pigments or filers.

Typical formulations for film-forming compositions are described in thefollowing U.S. patents, U.S. 3,261,796,

U.S. 2,868,752, U.S. 2,868,754, U.S. 2,787,603, U.S. 3,113,038 and U.S.3,032,521, and in Formulation of Organic Coatings by N. I. Gaynes, D.Van Nostrand Co., Inc. (1967).

One type of film-former which can be used, especially when thecomposition is a latex, is one composed of about 50-100% by weight of anamino ester polymer which may be defined as a vinyl addition polymerhaving attached to the carbon-carbon chain monovalent radicals of theformulas wherein R is selected from the group consisting of hydro= gen,benzyl and 0 -0 alkyl radicals, and R and R are selected individuallyfrom the group consisting of hydrogen, benzyl, aryl and C -C alkylradicals, and R is selected from the group consisting of hydrogen and C-C alkyl radicals. In this preferred kind of composition, about 150% byweight of the film-former can be composed of another film-former whichone skilled in the art can select as having suitable compatibility withsaid amino-ester polymer. Said amino ester polymer can be prepared byvarious methods well-known in the art; for example, according to theprocedure described in U.S. Pat. 3,261,796.

Another useful type of film-former to use in both the latex and solutioncompositions is one composed of about 50-100% by weight of an acrylicpolymer selected from the group consisting of poly(alkylacrylates),poly(alkylmethacrylates), and copolymers of an alkylacrylate and analkylmethacrylate.

Other useful film-formers are alkyd resins, oil-modified alkyd resins,formaldehyde condensate resins, epoxy resins, cellulose ester resins,shellac, vinyl chloride resins, acrylic acid copolymers, polyurethanes,acrylonitrile/alkyl acrylate copolymers, acryloxy alkyl-oxazolideneresins, and mixtures of two or more such film-formers.

For aerosol spray application, the composition can be packaged in knownaerosol containers along with any suitable propellant, for example,dichlorodifluoromethane.

The composition can contain one or more of the additives known to beuseful in film-forming compositions,

for example curing agents, driers, anti-freeze agents, pigments, wettingagents, anti-foamers, coalescent agents, odor controllers, abactericide, plasticizers, stabilizers, viscosity controllers,surfactants and anti-settling agents. The use of a bactericide is oftenparticularly desirable to complement the fungicidal compounds inprotecting the film-forming composition both in the can and onceapplied.

The active fungicide mixture can be incorporated into the film-formingcomposition in a variety of ways as will be apparent to one skilled inthe art. For example, the mixture can be added as a fine powder to theotherwise completed formulation, and the composition stirred until auniform mixture is obtained. Alternatively, the powdered mixture may beblended with the film-former or with the pigment if one is used, priorto formulation.

It is particularly desirable to incorporate the fungicide mixture intothe film-forming composition prior to any grinding or blending stepwhich would normally be done in preparing the formulation. In this way,the fungicide mixture is uniformly dispersed and no extra grinding orblending step is required.

A preferred procedure for paint, formulations, where the pigment must beground or disaggregated and dispersed in the vehicle, is to add thefungicide mixture prior to this grinding step.

In the interest of avoiding any undue harm to the active ingredients,the compositions of the invention preferably have a pH of about 1-10 anda processing temperature informing the solid film of less than 200 C. ifthe temperature is to be applied over a period of several hours, or ifshorter times are involved, temperatures up to 300 C. can be tolerated.

The composition can be formed into solid films or coatings by anysuitable known coating or film-forming method; for example, spraying,rolling, brushing, knifespreading, dipping, calendering, extruding,electrocoating, flow coating, or by a powder coating process wherein alayer of powdered coating composition is converted to a solid film(e.g., by a heating or hot-pressing method followed by cooling).However, theprocessing limitation previously set forth should beconsidered in utilizing these methods.

Paints, lacquers, adhesives and other types of filmforming compositionsare obtainable according to the present invention which have beneficialutility for the preparation of solid films and coatings. For example,these compositions enable one to prepare coatings having a verydesirable combination of properties including (1) effective initialfungicidal characteristics, (2) low toxicity to humans and warm-bloodedanimals, (3) satisfactory durability, adhesion, appearance and the like;(4) reasonable cost, (5) surprising ability to prevent or inhibit growthof fungi even after repeated exposure to rain and sunlight.

The compositions are very useful for coating articles and surfaces whichare likely to be .used under conditions which favor the growth of fungi,for example, in warm, humid areas. The utility of the compositions isespecially beneficial in applications where low toxicity to humans andwarm-blooded animals is important, for example, in coating the interiorof buildings used for the manufacture of foods and medicines.

A variety of substrates may be protected by the incorporation of thecompounds of this invention into filmforming compositions which are thenapplied to the substrate and result in an adherent, solidified layer.Wood, fabric, metal, leather, polymer coated or polymeric sheetmaterials, fiber board, paper and other industrial materials areprotected from unsightly stain and destructive decay caused by fungi.

The following examples are olfered to illustrate the film-formingcompositions of the invention.

6 EXAMPLE 1 A latex house paint formulation contains the followingingredients Parts by weight The above materials are ground in ahigh-speed mill and let down, at a slower speed, as follows:

1 Parts by weight Acrylic resin: Rhoplex .AC-388 (50%), sold by Rohm &Haas 459.8 Antifoamer: Nopco NDW 1 Premix:

Ammonium hydroxide (28%) 2 Tributyl phosphate 11.5 Propylene glycol 35Water and/or hydroxyethyl cellulose (2.5 17.5

To 1000 parts of the paint formulation described above is added 2 partsof finely divided 35 microns) 2(4- thiazoyl)benzimidazole and 6 parts ofethylenebis-(dithiocarbamic acid), zinc salt. The resulting mixture isthen thoroughly mixed.

Clapboard siding can be painted with two coats of the completedlatexi'paint, using an ordinary paint brush. The paint film,after'lbeing allowed to air dry and age under ordinary atmosphericconditions will have excellent resistance to fungal attack, cracking andblistering and good retention of appearance in general. 1

The clapboard" siding substrate can be eiiiib'r new or a siding that hasbeen previously painted. y

Equal weightsof the following compounds be substituted for theethylenebis(dithiocarbamic acid), zinc salt: e

dimethylditiiiocarbamic acid, zinc salt 3,4',5-tribrotno salicylanilide.

EXAMPLE 2 An oil base house paint formulation containing the followingingredients is used in the following test.

. Parts by weight TI-pure R-966 (titanium dioxide) 300 Talc, stir-ingrade 315 Long oil alkyd, Dyal )MC-Cl29,"sold by Sherwin- Williams Co.400 24% lead naphthenate 6.9 6% manganese naphthenate 1.4 Heavy mineralspirits 169 To 1000 parts of the paint formulation described above isadded 2 parts of 2-(4-thiazoyl)benzimidazole and 7.5 partsethylenebis-(dithiocarbamic) acid, zinc salt. The resulting mixture isthoroughly mixed. A clapboard siding can be painted with two coats ofthis fungicidal oil base formulation, using an ordinary paintbrush.After the paint film is allowed to dry, the clapboard will be resistantto fungal attack.

An equal weight of the following compound can be substituted for theethylenebis(dithiocarbamic acid), zinc salt:

3,4',5-tribromo salicylanilide.

EXAMPLE 3 A latex house paint formulation contains the followingingredients:

Parts by weight Hydroxyethyl cellulose (2.5% solution) 85 Water 68.5Nonionic dispersing agent: Tamol 7 31 (25%), sold by Rohm & Haas 15Wetting agent: Triton CF-lO, sold by Rohm &

Haas 2.5 Antifoamer: Nopco NDW, sold by Nopco 1 Ethylene glycol 25Non-chalking rutile titanium dioxide 250 Talc 203.7

The above materials are ground in a high-speed mill and let down, at aslower speed, as follows:

Parts by weight Acrylic resin: Rhoplex AC-388 (50%) 390.8 Long oilalkyd: Cargill 7700, sold by Cargill,

Inc. 30.8 Antifoamer: Nopco NDW 1 Premix:

Ammonium hydroxide (28%) 2 Tributyl phosphate 9.8 Propylene glycol 35Water and/ or hydroxyethyl cellulose (2.5 53.5

To 1000 parts of the paint formulation described above is added 1 partof finely divided 35 microns) 2-(4- thiazoyl)benzimidazole and 1 part2-mercaptopyridine-N- oxide, zinc salt. The resulting mixture is thenthoroughly mixed.

A clapboard siding can be painted with two coats of the completed alkydmodified latex paint, using an ordinary paint brush. The paint filmafter being allowed to air dry and age under ordinary atmosphericconditions will have excellent resistance to fungal attack.

Equal weights of the following compounds can be substituted for theZ-mercaptopyridine-N-oxide, zinc salt:

tributyltin fluoride; tributyltin oxide.

EXAMPLE 4 A latex house paint formulation contains the followingingredients:

Parts by weight Water 65 Ethylene glycol 35 Anionic dispersing agent:Tarnol 850, sold by Rohm & Haas m. 10 Nonionic wetting agent: IgepalCTA-639, sold by GAF Corp 3 Antifoamer: Colloid 677, sold by Colloids,Inc. l Thickener: Natrosol 250 HR (1.5% solution, sold by Hercules, Inc.165 Non-chalking rutile titanium dioxide 275 Extender: Optiwite, sold byBurgess, Inc. 35 Celite 281, sold by Johns-Manville 25 The abovematerials are ground in a high-speed mill and let down, at a slowerspeed, as follows:

Parts by weight Water 46 Vinyl acrylic resin: Resyn 2345, sold byNational Starch and Chemical Corp 364 Nonionic wetting agent: IgepalCTA-639 6.5- Antifoamer: Colloid 677 1.5 Coalescent: Carbinol Acetate,sold by Union Carbide l2 Thickener: Natrosol 250 HR (1.5% solution) 66To 1000 parts of the paint formulation described above is added to 0.5parts of finely divided 25 microns) 4 (4 thiazoyDbenzimidazole and 5parts dimethyldithiocarbamic acid, zinc salt. The resulting mixture isthen thoroughly mixed.

A clapboard siding can be painted with two coats of the completed latexpaint, using an ordinary paint brush. The paint film after being allowedto air dry and age under ordinary atmospheric conditions will haveexce1-= lent resistance to fungal attack.

Equal weights of the following compounds can be substituted for thedimethyldithiocarbamic acid, zinc salt:

ethylenebis(dithiocarbamic acid), zinc salt;3,4,S-tribromosalicylanilide.

EXAMPLE 5 A latex house paint formulation contains the follow ingingredients:

Parts by weight Water 65 Ethylene glycol 35 Anionic dispersing agent:Tamol 850, sold by Rohm & Haas 10 Nonionic Jail ?EQEBZF'fZLQi5585535153;

GAF Corp. 3

Antifoamer: Colloid 677, sold by Colloids, Inc. 1 Thickener: Natrosol250 HR (1.5% solution), sold by Hercules, Inc. Non-chalking rutiletitanium dioxide 275 Extender: Optiwite, sold by Burgess, Inc. 35 Celite281, sold by Johns-Manville 25 The above materials are ground in ahigh-speed mill and let down, at a slower speed, as follows:

Parts by weight Water 46 Vinyl acrylic resin: Resyn 2345, sold byNational Starch and Chemical Corp. 275 Nonionic wetting agent: IgepalCTA-639 6.5 Dryer:

6% cobalt naphthanate, sold by Nuodex, Inc. 1.5 24% lead naphthanate 3.0Long oil alkyd: Cargill 7700, sold by Cargill,

Inc. 37.0 Antifoamer: Colloid 677 1.5 Coalescent: Carbinol Acetate, soldby Union Carbide l2 Thickener: Natrosol 250 HR (1.5% solution) 66 Water26.5

To 1000 parts of the paint formulation described above is added 5 partsof finely divided 40 microns) '2-(4-thiazoyl)benzimidazole and 0.2 partsof 2-mercaptopyridine-N-oxide, zinc salt. The resulting mixture is thenthoroughly mixed.

A clapboard siding can be painted with two coats of the completed alkydmodified latex paint, using an ordinary paint brush. The paint filmafter being allowed to air dry and age under ordinary atmosphericconditions will have excellent resistance to fungal attack.

Equal weights of the following compounds can be sub-= stituted for the2-mercaptopyridine-N-oxide, zinc salt:

tributyltin fluoride; tributyltin oxide.

benzimidazole and 5 to 50,000 p.p.rn. by weight of a second fungicide ormixtures thereof selected from:

(i) ethylenebis(dithiocarbamie acid), zinc salt,

(ii) dimethyldithiocarbamic acid, zinc salt,

(iii) 3,4',5-tribromo salicylanilide,

(iv) Z-mercaptopyridine-N-oxide, zinc salt,

(v) tributyltin fluoride, and

(vi) tributyltin oxide.

3. The composition of claim 2 in the form of a liquid coatingcomposition wherein the film-former and compound are dispersed in theliquid.

4. The composition of claim 2 wherein the liquid is water and thefilm-former is suspended in the water.

5. The composition of claim 2 wherein the liquid is a volatile organicliquid and the film-former is in solution in said liquid.

6. A coated article comprising a substrate having in 10 adherencetherewith a solidified layer of the composition of claim 2.

7. The composition of claim 2 containing in addition 2.5 to 10 parts perhundred of zinc oxide.

References Cited UNITED STATES PATENTS 3,017,415 1/1962 Sarett et al.106l5 AF 3,350,211 10/1967 Greenwald 106-15 AF HARRY WONG, 111., PrimaryExaminer U.S. Cl. X.R.

117-127, 138.8, 140, 142, 147; 260-22 CB, 29.6 R,

